A need exists to find better methods to make oligomers and polymers from monomers. For example, some polymerization methods may work better for some monomers compared to other monomers. To the extent the polymerization method is limited, then commercial applications of the polymers are limited because in many cases the precise properties of the polymers need to be tailored for a particular application. Fine tailoring of polymer properties can be achieved by fine-tuning the structures of the monomers and polymers. This fine tuning includes, for example, microstructure and regioregularity considerations.
In particular, a need exists to develop better polymerization methods for making conducting polymers, or polymers having conjugated backbones. These include for example polythiophene, polyphenylene, polyacetylene, poly(phenylene vinylene), polyaniline, polypyrrole, polyfluorene, and derivatives thereof. These polymers can be difficult to make because in many cases they may become insoluble, infusible, or difficult to process. They may also suffer from instability. Structural inhomogeneity can become a problem. In many cases, the polymers need to be doped before they can be used. Conducting polymers can be used in applications such as, for example, transistors, light emitting devices (OLEDs and PLEDs), solar cells, and sensors. A particularly important example of conducting polymer is the polythiophene family, which includes homopolymers, copolymers, and block copolymers, see for example, U.S. Pat. No. 6,602,974 (Carnegie Mellon University). Also particularly important are polyfluorenes. See for example U.S. Pat. No. 5,900,327 (Uniax)
One example of a commercially useful synthesis of conducting polymer can be found in U.S. Pat. No. 6,166,172 to McCullough et al. (sometimes called the “GRIM” method). In particular, this method can be used to prepare regioregular polythiophenes (see for example FIG. 8 in the present application below). In this patent, use of organomagnesium reagents are described in the conversion of monomers to polymers using metal-halogen exchange, including magnesium-bromine exchange. However, limits and slowness of magnesium-bromine exchange are known as noted in U.S. Patent Publication 2005/0218532 to Knochel et al. Organic iodides may not be possible because of lack of availability or expense. In the prior art, synthesis of polyfluorenes and other conducting polymers has been carried out by the Yamamoto methods and modified Suzuki methods. Difficulties in present methods are described in for example Kappaun et al., J. Polym. Sci., Polym. Chem., Vol. 44, 2130-2138 (2006).
A need exists to improve upon these methods, particularly in ways that facilitate commercialization.